Should it be a concern if my baby is 8m old and doesn't bear any weight on his legs at all? His legs will bent if we try to put him on standing position. Most babies seem to be able to do that by this age.

8 months old is still early. By 1 years old, your baby need to stand with support, he don't need to walk on his own or support, but minimum is can stand on his stand with support. That is by 1 year old like that. If not, can drag a bit of time, and monitor again, see need to seek help from doctor or not. If baby can stand on his stand with support, don't worry too much, sooner or later, baby will walk on his own.